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180* vs 195* Thermostat


Guest wally888

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Guest wally888

All figures when OAT above 90* F.<BR>I have previously replaced 195* w/ 180* in two 89's. Results were the temp on the CRT was generally, 90+ percent of the time, 180* instead of 195*. The cars would sometimes briefly show 203* but before changing I often saw 208*, 213* and even 224* on my 133k, 89.<BR> My 91 ran at 12 o'clock about 90% of the time w/ a 195* and would climb to 2 o'clock on occassion , once or twice to 3 o'clock.<BR> I have replaced the 91, 195 w/ a 180 but the results are somewhat confusing.<BR> Results: Car stills runs at 12 O'clock 90+ % of the time. ( May flicker back one click momentarily but is seldom and never stays there.) I detect little difference re. how often it reads 2 or 3 O'clock?<BR> Seems if my new Thermo was starting to open at 180 vs 195, the gage would be at 11 O'clock most of the time?

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Can't rely on the bouncing dashes. Just had my cooling system redone, and it's noted in big type on the repair order that the temp gage is a full dash higher than what a thermometer in the water flow shows. They installed a 180-degreee stat and, when comparing it to the repair manual's calculations, what they call "digital madness" shows 10 degrees higher than it actually measures. They found the same thing with the oil pressure gage, and recommended a separate set of gages, ala Mustang's Pony Pack.<P>Jerry

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Were the temperatures at a steady elevated cruise speed or in urban type traffic? If the fan program hasn't been changed, the engine temp. without steady cooling air flow will still run warmer than you want. I would agree the digital readout is an approximation, although it should read cooler by a bar or possibly two if air flow is available. Even with my fan code changed, my 160 T'Stat will still run at about the 11 o'clock position unless I am out in the open where it drops to 10 oclock and ambiant air in the 80 deg.F. range.

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Guest wally888

Guess my driving routes resemble a homing pigeon's that is dropped off at the same place everytime.<BR> The OAT, the route(s), the driving speed and the gauge readings(behavior) were practically identical w/ both thermostats.<BR> I, as Hal stated, expected the 180* thermo. to cause the gauge reading to drop to 11 O'clock at steady cruise over 50 mph.<BR>Does not!<BR> Even if the gauge presents only an approximation, I would expect lowering the thermo 15* would lower the gauge reading.<BR> <BR> I will try another 180* thermo...........and report.

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Similar experience.<BR>180 degree and still runs 190ish and in stop and go have seen 224 though 214 is all too common.<P>Fix, the fans have to come on sooner to high speed.

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Prom change for fans is easy, just four bytes (well, six since I also raise the cut-off mph).<P>Otherwise the only way to determine the steady state temperature is in about ten miles at cruise controlled 60-70 mph - stock fans do not come on much below 100C/212F.<P>My rule of thumb is that a good cooling system will maintain engine temperature at 100F over OAT. A superb one can manage 85-90F but everything must be at optimum. <P>In stop and go traffic at 95F (98-100F road) I typically see 191-193F with the a/c on (and HI fans enguaged) which drops back on the Interstate.<P>Am aggravating things a bit with the bra but consider this within acceptable limits. <P>I do consider the Reatta cooling system marginal for the car in the first place (radiator area is a good 10% smaller than Bonneville) but my experience with 3800s is that they will run cool if given half a chance.<P>ps 88 has bars also, they are just vertical. Mine runs on the same bar (fourth ?) whether 180 or 200. To GM, "normal" seems to extend to 220F.<p>[ 08-24-2002: Message edited by: padgett ]

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Guest wally888

Ditto Harry's question?<BR> Will put in another 180 today.<BR> Someone? The 91 R. runs at a higher RPM in all gears than previous models but has same cooling system! Shouldn't it tend to run hotter?

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Well, first you need a computer which if reading this you probably already have.<P>Next read <a href="http://www.thirdgen.org/newdesign/tech/promintro.shtml">this article</a> in its entirety. Read it twice.<P>Reattas all use specific $5B PROMs. All use P4 8192 baud data streams (not important for reprogramming but for ALDL tools. <P>Of course all Reattas have a built in Scan Tool so you do not need one unless you want recording. I use two of these - an OTC 2000 with 1993 cartridge and the unobtainable special PC cable. <P>Or you can by a copy of <a href="http://216.230.203.183/auto/auto.htm">Diacom</a> which includes all cables. Note that this is only for C3, P4, & P6 cars and not for OBD II (why updates stop at 1995).<P>Next you need a PROM reader programmer like <a href="http://www.xtronics.com/memory/EPROM.htm">this.</a><P>Then you need a UV Eraser. I have the <a href="http://www.digikey.com/scripts/us/dksus.dll?Detail?Ref=27934&Row=154292">basic one</a> though some prefer to spend a few more dollars for <a href="http://www.digikey.com/scripts/us/dksus.dll?Detail?Ref=27934&Row=154293">one with a timer</a>. I usually erase the 27C256 for about 50 minutes.<P>Finally, you will need to make a CalPack to Prom Programmer adapter. Easiest is to modify a 34 Pin Header. See <a href="http://www.thirdgen.org/newdesign/tech/promintro.shtml">option two</a>. <BR>And that is all you need - can just dump the PROM to a file, edit with DEBUG, erase the PROM, and reprogram it.<P>All of the above (with the exception of the scan tools) can be had for right on U$200.<P>Now if you want to trade money for time and have a program to do it all for you then I suggest the <a href="http://www.tunercat.com/"> Tuner Cat</a> suite (you just really need the tuner and appropriate definition file(s)).<P>I helped develop the <a href="http://www.tunercat.com/tnr_desc/ecm_sup.html#buick">$5B plug-ins</a> but derive no revenue from TC (though am angling for help with decoding the BCM). <P>Note that there are two sets for the Reatta: 88 ($5B1) and 89-91 ($5B2). Note also that you <B><I>must</I></B> use the right set (offsets) or can really screw things up. They just came out with a definition for the 93-94 L67 if you lean that way.<P>Would also suggest having at least one spare CalPack just in case things go rong.<P>ps if anyone needs a bin of the ANCX (factory update for 88 Reatta only), I can e-mail.<P>More than you ever wanted to know ?<P>ps Wally: 91 runs at 11% (3.33/2.97) higher RPM (about 2220 at 70 instead of 2000) but has a lighter load. Difference will be slight particularly if tires are 225x60x16 (common size) and not original 215x60x16 (not so common size).<p>[ 08-24-2002: Message edited by: padgett ]

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  • 4 weeks later...

Just checking, but changing the thermostat, after bleeding out some coolant, is just removing the one bolt, slipping in the new thermostat and gasket and tightening it down, right? I have replaced them on chev 350's, but they have two bolts holding the housing down, not one. It appears the one bolt on the 3800 probably is to make it easier around the throttlebody (now why would GM think of that?) I don't have a copy of the FSM (yet), so I would appreciate an alert if I am missing something that I might screw up. It appears the damn thing is stuck open, the car cools down to 145 degrees on the highway. Thanks.

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Guest wally888

I bolt, yes. A gasket and an"O" Ring, I think. On 91 there are two bolts, a gasket and a split interior U seal.

Be careful as it is very easy to damage the TPS while removing/installing.

I syphoned a little coolant , w/ a piece of vac hose, from radiator cap opening. Changed in the garage w/o spilling a drop. For those who have never syphoned , ahem!, gas, you don't have to suck on the hose. Fill w/ water , hold finger over top end, insert in radiator. A vac hose will go down 6 inches or so, on the inside edge.

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YUP BEEN THERE, DONE THAT frown.gif

You are installing it on a slight angle.

Remove and lubricate housing and opening with what ever you have around.

Line up the housing over the opening and use the biggest longest screwdriver you have and slowly on all sides start to push the housing down. Go around the housing in 1/4 turn increments and when it is 3/4 of the way into the hole use the bolt to tighten it down the final little bit.

You should probably start with the edge farthest from you and the rad.

Have fun

Frankly I wish they spent the extra 1.25 cents and used two bolts.

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Second thought.

As the bolt starts to tighten up use the screwdriver to push down the other side so it will not jam in the opening.

Just try it and you will get the technique.

then try a BIG bjt138.gif

Or a 12 pounder 15457_lg.jpg

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Heh, heh, heh! grin.gif

I love this. Yeah, she got me that way too, but there is a trick to getting the neck over the thermo and in it's housing... <span style="font-weight: bold">SMALL FINGERS!!!</span>. Was this car's engine compartment designed by women? Ever try to get the PVC valve out with your hands? More importantly, ever succeded?

I went to the 180's a bit ago in my '90 and have witnessed the same, barely any change (one tick left on the norm). I've had it tested at a "radiator shop" after finally fixing the overheating problem (it was the water pump bearing going up for those dealing with the "always hot" prob). If you need, email me and I'll give details on all of that.

Anyway, shop said running typically at about 180-187 degrees before opening (like it should've) while at idle and when asked if radiator should be replaced with a 2 or 3 core, was told that the single core GM installed has better efficiency of any aftermarket 2-3 core he knows of. Still would run about 2-3 o'clock in stop and go (sometimes even to one tick before redline) til I went on my vacation and they couldn't figure why. Had tranny and oil pans dropped for filter, fluid, gasket, and sensor replacements (knowing I was taking her over 3400miles and not wanting any surprises), and...

[color:\\"red\\"] <span style="font-weight: bold">PRESTO!!!! No more tears!!</span> or at least no more overheating. Just thought some of y'all might want to know. The silliest little things seem to make a huge difference with the Reatta, doesn't it?

Regards to you all,

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Consultants 1

Long time no hear.

As I recall your problems were about a year and a bit ago.

Glad that you got it fixed. A water pump is an easy DIY job if you are so inclinded

Robert

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Over a year ago on this board, I posted a small observation regarding coolant systems and internal temperatures my 90. Exerpt:

ED04 Temp C - Bar Reading on IPC

84 - 12

99 - 1 Bar Right

102 - 2 Bars Right

105 - 3 Bars Right

109 - 4 Bars Right

ED04 Temp C - Coolant Sensor Value (in Ohms)

85 - 261

87 - 253

90 - 233

95 - 197

100 - 178

105 - 164

110 - 126

Note that I've seen my IPC Bar Reatout vary +/- 2 or more degrees for a nominal bar reading. This would indicate that the IPC and ED04 sensor are not exactly harmonious, nor are they logrithmic.

Also, inasmuch as the IPC Bar Graph provides typical represtentation of the temperature, I would imagine that the readings vary from IPC to IPC, given component values.

Regarding the above ED04 and Ohmic values of the sensor, if plotted on Excel, it does exhibit a linear rate. So, at least in my vehicle, the sensor responded with correspondingly less resistance given the rise in temperature.

--Tom

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Guest Greg Ross

Padgetts' solution, though complex to us Laymen with the adjusting of the "Fan On/ Fan Off" parameters solved the problem of my overheating concerns. After several months here in Loosiana and the escalating ambient temps I was becoming increasingly concerned about, the 180 deg. thermostat and modified ECM PROM for Fan settings cured me.

We now run 179 deg. with A/C off and 185 to 187 deg. with the A/C on. Much healthier I do believe.

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Tom J., Padgett..........

Do these #'s make sense? *F

84 - 12 = 183

99 - 1 Bar Right 210

102 - 2 Bars Right 215

105 - 3 Bars Right 221

109 - 4 Bars Right 228

27*'s for 1 click then 5*'s

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Yes, Wally, they seem about right.

Remember, the 'bar' reading on the IPC is apparently *NOT* linear. I wouldn't put too much stock in the interpretation of bars vs temp.

What I *WOULD* do is enter the OBD, and observe ED04.

By the way, still waiting for D. L. Mc Crea to come through on his 'water pump bearing' issue.

--Tom

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Sorry Robert, Tom, and others,

Just figured out how to get my posts to show since the update to the site. Haven't had much free time to keep up with everyone and had H*LL trying to get it together when I did. Good to hear from you guys and be back (somewhat) on the board. I wasn't able to post an edit to my last posting...

The Catalytic Converter also was a significant cog in the works of cooling her off. There was a big ball of white plaster in there and a bunch of powder, that was about all. Strange, it's prob been like that for the last three years or so, and I never had emmission or power probs, just heat. I've even dyno'd her and was getting about 164bhp before I started tweaking. Big question... HOW!!!! crazy.gif

Anyway, that was part of that whole "before the road-trip" maintenance headache. Total of all repairs - just over $650.00 (which was cheap, considering it was the only maintenance done in over a year, besides oil and the like).

The water pump bearing...

Simplest (and cheapest) way to deal with it... new pump for $60 and about 30 minutes of knucklebusting fun. Serpentine belt slipped off due to wobbling of pulley after I stopped and tried to restart (immediate indication of this is when you turn the wheel while stopped and it doesn't turn easily).

<span style="font-weight: bold">TAKE SPECIAL NOTE OF SERPENTINE BELT'S ROUTING!</span> Draw a pic if you have to. It's not hard to figure out, but it's a real pain and a waste of time if you have to.

I put a new GatorBack brand belt (at $80) on her, but didn't need it at the time, just paranoid. Basically, I would just suggest a "belt breaker bar", which is nothing more than a flat thin bar with a 3/8" socket adapter on the end. Makes moving the belt tensioner a whole lot easier than the old "tire iron and muscle" way we used to move the tensioner. The water pump's bolts were easy to get to, but two different sizes (I have to look the sizes up and post an edit). The pump just slid off easily, I used a razor blade to clean off the old gasketing and some Permatex Gold to seal the new water pump on.

Unscrew all bolts most of the way, but leave two or three in loosely to keep pump on while using the ratchet, then unscrew last three with fingers , holding pump up with other hand. Replacement goes on pretty much in reverse, starting with all bolts finger tight to hold the daoggone thing in place, then tighten up the bolts with a ratchet in a starlike pattern. Use the breaker bar to replace belt after rerouting and you're done. Not really hard at all.

Hey, a simpleton like me did it! shocked.gif If you need any more details, email me at the Consultants_1@hotmail address or Tom, you can just call me, you know. smile.gif

High Regards to you all.

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